Egg cooker



EGG COOKER Filed June 26, 1950 2 Sheets-Sheet l INVENTOR.

M /KM.

S p 21, 1954 H. HARRISON 2,689,516

EGG COOKER Filed June 26, 1950 2 Sheets-Sheet 2 INVENTOR.

I Mm, amg/wm ATTORNEYS period of time, such as three minutes.

Patented Sept. 21,1954

UNITED STATES PATENT OFFICE EGG COOKER Henry Harrison, Port Washington, N. Y. Application June 26, 1950, Serial No. 170,378

My invention relates generallyto devices for performing processes in which an article, such as an eg is removed from or immersed in a liquid, such as boiling water, for a controlled It relates particularly to auxiliary devices of this sort, which hold, dip, and. raise the article to be treated, but do not control the condition of the liquid.

It is a major object of my invention to provide a simple, durable, easily manipulated auxiliary device of this sort which does not depend for its operation on the precise amount or condition of the liquid. It is a specific object of my invention to provide a compact, attractive, adjustable, auxiliary device particularly adapted for timing and controlling the cooking of eggs in boiling water.

I achieve these objects by means of a float, which supports the article being processed submerged in the liquid for a predetermined length of time, and then raises it and supports it-out of the liquid; or the article may "be supported above the liquid for a predetermined period and then lowered and supported submerged in theliquid. I

A special design of float is necessary to achieve this action, and the nature and limitations of this design can be understood from the following description by anyone skilled in the art of float ing vessels.

The description and the attached drawing refer more or less specifically to an egg cooker, but the principles disclosed can easily be applied to other devices. I therefore wish this disclosure to be regarded merely as an illustrative example of my invention, which is more precisely set forth in the appended claims.

In this device I prefer to use gravity-as the sole source of motive power. It is, then, necessary to have two stable equilibrium positions of the float; an initial position in which the article being processed or treated may be heldsubmerged in the liquid; and a final position in which the article may be supported above the surface of the liquid. If in the initial position there is to be energy available to operate time interval measuring means and to do the necessary work of lifting the article out of the liquid, the initial stable equilibrium position can not be the position of minimum potential energy. Following common usage, we will use the termmetastable to describe this initial position. Within limits of angular excursion or movement, the body will return to this metastable position, but if these limits are exceeded the body will gravitate to a 4 Claims. (01. 99--336) different stable position. This kind of behavior is common in many kinds of floating ,vessels. A vessel may have any number of metastable or stable positions, depending on its shape, its buoyancy, and the positionof itscenter of gravity.

* For the purpose of this invention, it necessary that the floating system, comprising the floating body and the article attached .to it, have at least one metastable position and at least one stable position. The final position is necessarily of lower energy than the initial position, for there must be sufficient energy diiference to operate the timing means, and to lift the article out of the liquid; but it may also be a metastable position.

A specific embodiment of my invention, intended for cooking eggs in boiling water, is shown in ther'accompanying drawing wherein:

Figure 1 is a perspectivedrawmgofthe float in its initial position ina pan of boiling water;

Figure v2 is :a partial perspective view of the same float in its final or inverted .position;

Figure 3 is a diagram which assists in understanding the method .of designing such a float;

Figure 4 is a cross sectional-view :of oneform of this invention;

Figure '5 is .a cross sectional .view of a modified form of this invention; and

Figure 6 is a cross sectional view of a second modified form of thisinvention.

In Figure 1, the floating 'body .or member I, carrying two :eggs 2, is floating in its metastable position .on the .hot water 3 in the pan 4. The weight :5, which is mounted in an eccentric position on a projection of fioat I, would normally tip the float over, but this is prevented by the Weight of the :body of 'water-6, trapped in a reservoir in float I. This water 6 isat a higher level than the surrounding water 3. It is allowed to drain slowly out through hole L'which is partially closed by the adjustable closure 8. This combination of water '6, passage l, in the retaining partition, and eccentric weight ,5 constitutes a time responsive system which controls the length of time thefloat remains upright in its metastable position. As the water ,6 runs out through hole 1 its counterbalancing effect diminishes, and weight '5 tilts float l farther and farther back. Finally edge'9 dips below the surface, and the metastable position thereupon becomes unstable. The float tumbles over backward and turns upside down, raisingthe two eggs out .of the hot water.

. Figure 2 shows the float I upside down, in its stable position. Only one egg '2 is shown, the

3 other having been removed to make details of the bottom of the float visible. The float is still buoyed up on hot water 3, but weight 5 is now submerged, as is edge 9. Spring strap l holds the egg or eggs in the recesses ll. Channels [2 are provided to allow the escape of air which might otherwise be trapped in recesses H when the float is in an upright position.

When using this egg cooker, the cook first sets the opening of passage 1 to give the desired time of cooking. He then inserts the eggs in the recesses II, where they are held by spring strap [0. Holding float I by weight 5, he then dips it in the hot water 3, allowing water 6 to flll the reservoir. He now releases the float, and it floats in its metastable position, with the eggs cooking, submerged in the hot water.

During the cooking period, the water 6 slowly leaks out through passage 1. When the edge 9 goes below the surface and the float turns over, the eggs come out of the water. Cooking ceases, but the eggs stay warm. The float with the eggs can be grasped by the spring strap l0 and lifted out of the water. Each egg can be extracted by sliding a teaspoon under it.

Figure 3 shows how the stability of the float l may be analyzed. This is a method of analysis which is familiar to designers of floating vessels, and it is reviewed here as a means of explaining some of the features of this float.

According to Archimedes principle, the weight of the float l plus the liquid 6 in its reservoir is balanced by the weight of liquid 3 displaced. This condition establishes the depth at which the float is supported.

The angle at which the float will rest is determined by the position of zero torque. Torque is often calculated about the center of gravity of the float, because this is the point about which gravity exerts no torque. In Figure 3 the axes l4 and i5, fixed in the floating body, have been drawn through the center of gravity. The center of gravity is quite high because the weight 5, though less bulky than the rest of the float, is very much denser.

The torque about the center of gravity exerted by the liquid 3 is foundiby adding up' the torques contributed by all portions ds of the submerged surface. If i is a unit vector along axis M, which is the direction a: is measured; and 5 is a unit vector along the axis I5, which is the direction y is measured; and n is the unit vector normal to the surface element (is at (1:, y) and re is the density of the liquid 3; and D is the depth of ds below the surface of the liquid 3; and g is the gravitational constant; then the torque T1 acting about the center of gravity can be expressed by the following integral.

This integral is a function of the angle A between axis l5 and a vertical line It, because the limits of the integral, i. e., the points where the surface of the float intersects the surface of the liquid 3, and also the depth D depend on the angle A.

The portion of liquid 6 also exerts pressure and torque on the walls of the reservoir, which is part of the float. Thi torque T2 can be expressed by a similar integral over the surface liquid 6 touches. H is the additional height of liquid 6.

This integral is a function not only of A, which again appears in (D-l-H) and the limits of inte- 4 a io but also of the volume of liquid 6, which affects the same two quantities.

The condition of torsional equilibrium exists when T2 and T1 are equal and opposite. This may or may not be stable or metastable equilibrium. The equilibrium is stable or metastable when a small deviation in A from its equilibrium value results in an increment of torque tending to return it to equilibrium. Otherwise it is unstable.

Having reviewed the general considerations relating to stability we will see in Figure 3 how they aifect the design of this float. When one supposes a small counterclockwise increase in the angle A, the increment of torque from the left end of the float is also counterclockwise, for a small increase in submerged area at this end, together with a small increase in average presure, also takes place. At the right end of the float, the change is a small decrease in clockwise torque, corresponding to a small decrease in submerged area and small decrease in average pressure. Thus the effect of the submerged por tion of the ends of the float is generally unstabllizing, for the torque change assists the displacement, rather than opposing it. The flat bottom, however, has a stabilizing effect, for the pressure increases on the left and decreases on the right, producing a stabilizing clockwise torque opposing the counterclockwise displacement.

The balance between stabilizing and unstabilizing influences is controlled by the relative width to depth of displacement and by the height of the center of gravity. A high center of gravity affords a long lever arm for the end forces and thus tends to accentuate the unstabilizing influences. Nearly horizontal submerged area is more effective in stabilizing when it is near the edges, because then it has a longer lever arm.

The capacity of the reservoir for liquid 5 should be made reasonably large in order to make the precise densities and dimensions of the float reasonably free of close tolerances. It must not be made so large that the float becomes unstable and tips over clockwise when the reservoir is filled.

The head H may be made a predetermined function of the angle A by contouring the bottom of the float; Thus the curve l3 tends to keep the head H constant while the liquid 6 is running out. The head would tend to increase as liquid 6 runs out if the left end of the float were squared When the corner 9 submerges, a further unstabilizing influence is added, since the clockwise torque produced by that region of the float no longer increases. The float then tips over in a counterclockwise way. The torque remains counterclockwise until the weight 5 is hanging directly under the float I. This is the stable position of minimum potential energy.

Articles such as eggs which are fastened to a float such as the float of Figure 3 may affect its behavior. It happens that the average density of eggs is quite close to the density of water. Thus as long as they are submerged they have no great influence on the action of the float. As the float capsizes, however, they tend to exert a stabilizing influence. The center of gravity of the float should be put high enough to overcome this stabilizing influence. The situation is optimum if both the center of the eggs and the center of gravity of the float are reasonably high. Having the eggs rest in recesses I I, such as those of Figure 2, is helpful. c

'5 When the float is upside down and is supporting articles such as eggs above the liquid 3., it must, of course, have a total displacement .great enough to support its weight and the weight of therarticles it carries.

The foregoing discussion is suflicient to enable one skilled in the art of floating vessels to design an egg cooker according to my invention. There are some other lessbasicfeatures of the design which I have shown in Figures 1 and 2. Being free to choose the shape of the float within the rough outlines specified, I have sought by curving the' weight-supporting column to reduce splashing as the float capsizes, to provide a support for the device when it is not in the water, and to provide a handle'with pleasing lines. I have rounded the corners and curved the sides of the floatto make it fit in smaller pans and to make it appear smaller while remaining substantially the same size.

Although the models I have made are of varnished wood, economic reasons lead me to prefer the construction of Figure 4. In this construction the body of the float is a hollow shell, put together from two drawn pieces of aluminum or other ductile metal. The upper piece I! is joined to the lower piece l8 by a soldered or welded joint, or by a plastic cement, in the crack l9, which resists boiling water. The weight 5, of lead or similar dense material, may be cast in the upper part ll of the shell, and secured by indentations 29. The lower surface of the reservoir is formed in part ii. The recesses II and channels l2 are pressed into the lower portion l8 of the shell. The orifice l is punched through the part 3 which forms a wall of the. reservoir. The adjustable covert is rotatably riveted in I8 to partially cover hole 'i. The spring strap is riveted to the sides of part [8.

The contours formed in parts I! and I8 stiffen them so that they can better Withstand the internal pressure changes associated with heating and cooling the float. In addition it may be desirable to provide a small vent hole, preferably in the bottom of part [8, communicating with the inside of the shell; Through this hole air could easily pass out, driving any small amount of water before it, as the float, in its upright position, comes up to temperature. When the float has turned over, this vent is above the surface of the water, so that water does not tend to be drawn into the shell as it cools.

Figure shows a modified float 2 I supported by liquid 3 according to my invention, in which the liquid 22 runs into the reservoir through hole 1. The action of the system is driven by weight 5, which tends to keep the level of liquid 22 below the level of liquid 3. Contour l3 may again be used to control the head under which liquid flows through hole 1. When edge 9 sinks below the level of liquid 3, the system becomes unstable, and weight 5 swings down under float 2|.

Figure 6 shows another modified form of float 23 supported on liquid 3 according to my invention, in which the time responsive means is a sand clock or hour glass instead of a water clock as shown in the other figures. The sand clock consists of two chambers 24and 25 joined by a constricted passage 26. Sand 21, flowing from chamber 24 to chamber 25 through passage 25, displaces the center of gravity sidewise, causing the edge 9 to be submerged beneath the surface of liquid 3, and the weight 5 to swing around under the float. The time required for the metastable position to become unstable can be predetermined '6 by setting the eccentricity of the weight 5 with respect to the float 23 so that a predetermined weight of sand will cause edge 9 to be submerged.

I have described in the foregoing specification several structures according to my invention which are particularly suited to use in cooking eggs. It is my intention that these embodiments should be regarded as examples of the invention set forth in the following claims.

I claim:

1. A device of the class described including a liquid container, a supporting member floatable in the liquid container, said floatable member having an offset over-balancing weight projecting from the top thereof, time responsive means associated with said floatable member for shifting the center of gravity thereof, and means for connecting an article to be treated to the under side of said floatable member, said weight extending above the surface of the liquid and said article below the same when said floatable member is in an initial, metastable, freely floating position, said weight and said article being reversed when the floatable member is in its final stable, freely floating position, said time responsive means being operable for shifting the center of gravity of the floatable member in order to render the metastable floating position unstable when a predetermined time interval has elapsed and cause rotation of the floatable member about its center of gravity from the metastable floating position to the stable floating position so as to position the article above the surface of the liquid in the container.

2. A device of the class described including a liquid container, a supporting member floatable in the liquid container, said floatable member having a top formed on one side with a ballast chamber and on its opposite side with an overbalancing weight, time responsive means associated with said floatable member for laterally shifting the center of gravity thereof, the center of gravity of the ballast chamber being shifted when liquid is admitted thereto causing the metastable state to become unstable, and means for detachably connecting an article to be treated to the under side of said floatable member, said weight extending above the surface of the liquid and said article below the same when said floatable member is in an initial, metastable, freely floating position, said weight and said article being reversed when the floatable member is in its final stable, freely floating position, said time responsive means being operable for laterally shifting the center of gravity of the floatable member in order to render the metastable floating position unstable when a predetermined time interval has elapsed and cause rotation of the floatable member about its center of gravity from the metastable floating position to the stable floating position so as to position the article above the surface of the liquid in the container.

3. A device of the class described including a container having a treating liquid therein, a supporting member floatable in said liquid, said floatable member having a top formed on one side with a ballast chamber and on its opposite side with an over-balancing weight, means for detachably connecting at least one article to be treated to the under side of said floatable member, said weight extending above the surface of the liquid and the article to be treated below the surface of the liquid when said floatable member is in an initial, metastable, freely floating position, said weight extending below the surface of the aesazne liquid and said article above the same when the floatable member is in its final, stable, freely floating position, said ballast chamber being full of the liquid when the fioatable member is in its initial metastable position, said chamber having a restricted opening for discharging the liquid therefrom so as to laterally shift the center of gravity of the floatable member in order to render the metastable floating position unstable when a predetermined interval has elapsed and cause rotation of the floatable member about its center of gravity from its metastable floating position to its stable floating position so as to position the article above the surface of the liquid in the container.

4:. A device as called for in claim 1 in which the time responsive means includes a sand clock eccentrically positioned within the fioatable member and adjacent said weight, said clock having '8 upper and lower communicating compartments, and said clock being operable so that the sand in passing from the upper compartment to the lower compartment is moved laterally, thus shifting the center of gravity of the floatable member laterally so as to render the initial metastable floating position of the floatable member unstable.

References Cited in the file of this patent UNITED STATES PATENTS Kinney June 13, 1950 

